Extreme Networks ExtremeWare XOS 11.3, Руководство пользователя

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Route Redistribution
ExtremeWare XOS 11.3 Concepts Guide
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Split Horizon
Split horizon is a scheme for avoiding problems caused by including routes in updates sent to the
router from which the route was learned. Split horizon omits routes learned from a neighbor in updates
sent to that neighbor.
Poison Reverse
Like split horizon, poison reverse is a scheme for eliminating the possibility of loops in the routed
topology. In this case, a router advertises a route over the same interface that supplied the route, but the
route uses a hop count of 16, which defines that router as unreachable.
Triggered Updates
Triggered updates occur whenever a router changes the metric for a route. The router is required to
send an update message immediately, even if it is not yet time for a regular update message to be sent.
This generally results in faster convergence, but may also result in more RIP-related traffic.
Route Advertisement of VLANs
Virtual LANs (VLANs) that are configured with an IP address but are configured to not route IP or are
not configured to run RIP, do not have their subnets advertised by RIP. RIP advertises
only those
VLANs that are configured with an IP address, are configured to route IP, and run RIP.
RIP Version 1 Versus RIP Version 2
A new version of RIP, called RIP version 2, expands the functionality of RIP version 1 to include the
following:
●
Variable-length subnet masks (VLSMs).
●
Support for next-hop addresses, which allows for optimization of routes in certain environments.
●
Multicasting.
RIP version 2 packets can be multicast instead of being broadcast, reducing the load on hosts that do
not support routing protocols.
NOTE
If you are using RIP with supernetting/Classless Inter-Domain Routing (CIDR), you must use RIPv2 only.
Route Redistribution
More than one routing protocol can be enabled simultaneously on the switch. Route redistribution
allows the switch to exchange routes, including static routes, between the routing protocols.
Figure 66 is
an example of route redistribution between an OSPF AS and a RIP AS.